Unexpected positive intraoperative cultures (UPIC) at index osseointegration do not lead to increased postoperative infectious events

Abstract

Introduction: The most common complication following transcutaneous osseointegration for amputees is infection. Although an obvious source of contamination is the permanent stoma, operative site contamination at the time of implantation may be an additional source. This study investigates the impact of unexpected positive intraoperative cultures (UPIC) on postoperative infection. Methods: Charts were reviewed for 8 patients with UPIC and 22 patients with negative intraoperative cultures (NIC) who had at least 1 year of post-osseointegration follow-up. All patients had 24 h of routine postoperative antibiotic prophylaxis, with UPIC receiving additional antibiotics guided by culture results. The main outcome measure was postoperative infection intervention, which was graded as (0) none, (1) antibiotics unrelated to the initial surgery, (2) operative debridement with implant retention, or (3) implant removal. Results: The UPIC vs. NIC rate of infection management was as follows: Grade 0, 6/8 $=$ 75 % vs. 14/22 $=$ 64 %, p $=$ 0.682; Grade 1, 2/8 $=$ 25 % vs. 8/22 $=$ 36.4 % (Fisher's p $=$ 0.682); Grade 2, 1/8 = 12.5 % vs. 0/22 $=$ 0 % (Fisher's p $=$ 0.267); Grade 3, 0/8 $=$ 0 % vs. 1/22 $=$ 4.5 % (Fisher's p $=$ 1.000). No differences were statistically significant. Conclusions: UPIC at index osseointegration, managed with directed postoperative antibiotics, does not appear to increase the risk of additional infection management. The therapeutic benefit of providing additional directed antibiotics versus no additional antibiotics following UPIC is unknown and did not appear to increase the risk of other adverse outcomes in our cohort.

Figure 1

Osseointegration implant and clinical patient photograph. The Osseointegrated Prosthetic Limb (OPL) which was the implant used for nearly every patient in this study. It is a forged titanium alloy, stem-shaped implant whose surfaces have a plasma-sprayed coating, up to 0.5 mm thick, to promote bone ingrowth and rapid integration. The external portions of the collars are treated with titanium niobium oxynitride ceramic to promote smooth soft-tissue gliding, limiting the probability of symptomatic soft-tissue adhesion and tethering. Proximal fluted fins provide initial rotational stability, akin to a Wagner-style hip arthroplasty stem. (a) Exploded view with the components arranged at approximately the proximal–distal levels in which they would be once assembled and implanted in a patient who had undergone a femoral amputation: (1) proximal cap screw; (2) OPL body; (3) safety screw; (4) dual cone abutment adapter; (5) permanent locking propeller screw; (6) proximal connector; and (7) prosthetic connector. (b) Photograph of a 28-year-old male with bilateral transfemoral amputations, requiring a wheelchair for locomotion. (c) Preoperative left and right femur radiographs, assembled to portray patient's preoperative osteology. (d) Three months following osseointegration, the patient was fit with bilateral prosthetic legs. Note the transcutaneous nature of the skeletally linked prostheses. (e) Long standing radiographs of the patient with the osseointegrated implants connected to the prosthetic legs. Note that unlike many transfemoral amputees using a socket prosthesis whose hip joints are abducted against the socket liner, this patient's femurs are anatomically oriented with the hip, knee, and ankle in excellent mechanical alignment. (f) Photograph of patient standing without a walking aid 1 year after osseointegration.

Figure 2

UPIC patient who had additional surgery to manage infection. (a) Clinical photograph identifying the patient was unable to wear his prosthesis before surgery and was relegated to crutch ambulation because (b) the socket prosthesis caused painful skin ulcers. (c) He developed a sinus tract which was debrided 9 months after the index surgery. (d) Within 5 months, the patient was able to return to a higher level of activity than before osseointegration, seen here demonstrating the ability to plant on his osseointegrated leg in order to turn a dance partner.